Razors include two types commonly which are razors that the razor head is integrated with the handle, and razors that the razor head and the handle are detachable. Therein, the razor head of the former is directly fixed on the handle, while the razor head of the latter is connected with the handle via a connection part, and the handle is detachable and replaceable.
Generally, the current razor head includes an outer frame and a plurality of razor blade assemblies, and the razor blade assembly includes a razor blade holder and razor blades fixed on the razor blade holder. Positioning blocks are symmetrically formed on the two side walls of the outer frame, and the positioning blocks have a first plane for mounting and supporting the razor blade assemblies. And the positioning blocks are arranged with spaced each other and then form several grooves, the lower end of the razor blade holder is mounted within the groove, and a restricted buckle is mounted on the outer frame so as to maintain the razor blade assemblies in a predetermined position. Resilient arms are connected with the side wall of the positioning blocks, and each of resilient arms includes a leg part connected with the positioning block and a head part formed on the end of the leg part. The head part provides an upward elastic supporting force to the razor blade assemblies. While shaves, the razor blade assemblies can be maintained within the outer frame and moved up and down by pressing the head part, and the planes of the razor blades are parallel to the first plane during shaving.
Concretely, the upward force F that the head part applies to the razor blade holder is a linear function of a downward displacement Y: F=K×Y, wherein K is the spring constant (depended on the length L, inertia moment I and modulus of elasticity E of the resilient arm, K=L3/(3EI)) which is a constant, and Y=Yp+Yd, and Yp is the downward offset distance of the head part of the resilient arm after the razor blade assemblies and the restricted buckle assembled, Yd is the downward offset distance of the head part during shaving. Therefore, the degrees of the inclination angle between the leg part of the resilient arm and the first plane are the main factor that determines Yp which is the main factor determining the upward force F the head part applying to the razor blade holder, that is, the degrees of the inclination angle between the leg part and the first plane directly affect the upward force F that the head part applies to the razor blade holder.
However, the current outer frame of the razor head exist two drawbacks as following:
(a) The inclination angle between the leg part of the resilient arm and the first plane is too small, and the downward offset distance Yp of the head part of the resilient arm after the razor blade assemblies and the restricted buckle assembled is relative small, which cause the upward force F that the head part applies to the razor blade holder is too small. Thus, this outer frame has a poor using performance.
(b) The inclination angle between the leg part of the resilient arm and the first plane is too large, and the downward offset distance Yp of the head part of the resilient arm after the razor blade assemblies and the restricted buckle assembled is overlarge, thus the elastic deformation of the resilient arm is overlarge, which easily causes fractures of the resilient arm during shaving. Thus, this outer frame has a short lifetime.
Therefore, there is a need to provide an outer frame and a razor head with the same with good using performance and long lifetime.